kr starting issue..... once more!

[krnau 0]

Hello all! I have been having the following problem since I bought the car:

 

The car starts up PERFECTLY except when it has been stopped for more than 1 hour. However, if I leave it at night and start it next morning (or next afternoon etc), about 8-12hours or more later... it starts up perfectly.

 

This issue appears when the car has been sitting with the engine stopped from 1 to 8 (or a little more) hours. When this happens, it seems to be running on 3 cylinders from 8-12seconds (idleing at 400 - 600 - 400 - 600 rpm all of time)... but then, all of a sudden, it makes BRURURUMMM and idles correctly at 900-1000rpm :)

 

 

I have been testing it for a while in order to know WHEN does it exactly have this problem, and it doesn't matter if the oil temp is 50ºC, 80ºC, 90.... it mostly happens when it has been sitting from 1 to 6 (or maybe more) hours since it was stopped. However, if I start it up and the problem occurs; and then I stop it, and start it up again, it works fine :pukeright: :pukeright: :pukeright:

 

 

So all this things drive me to think about a malfunctioning WUR..... :mad2:

 

 

 

Bits replaced (all of them brand new) & tested:

 

1. Rebuilt Engine

2. Block sensors

3. Distributor Cap & Rotor arm

4. Fuel pumps (intank and outtank)

5. Fuel filters

6. All air pipes checked, no leaks

7. Starter motor

8. Fuel accumulator

9. Earth wires from "-" battery to engine head (read about this somewhere, but made no difference)

10. Ignition timing set correctly

11. Injector seals

12. Throttle position switch

13. ISV

 

And many other ones but I can't remember..

 

 

I need to say that all fuel pressures (system, etc) were checked and revised by a K-Jetronic master in a Bosch Service, but when it was checked this issue didn't disappear... so it might be worth a chech (I need some k-jet testing gauges... if anyone knew where to get them from..... :) )

 

 

 

Disconnected 5th injector makes the car start better (or it might be of my imagination :lol: )

 

 

 

NEW UPDATE

 

SInce all of his mostly happens with warm(ish) engine, and within 30minutes - 4 hours after shutting off the engine...

 

 

Yesterday, I decided to start it up, leave it for about 15 seconds idleing, and then shut it off. After 2 hours I came back to the car and WOW! it started up perfectly. I did it because in the case that the engine had been warmer than it was, it would have started up like on 3 cylinders... but it was stone cold, and started OK.

 

 

this takes me to think that fuel accumulator is OK?

it might be a WUR malfunction when it is hot)

engine temperature senders not very fine?

 

 

thanks :)

[davidwort 0]

does the fan run-on work OK? triggered by the little switch on the front left of the cam cover, this is intended to keep engine bay temps down to prevent fuel vapourising in the fuel lines causing exactly the problem you describe.

I believe the pressure accumulator should do a similar thing, by keeping the system pressure up, you also need to check the pressure the system is maintaining after engine-off for the specified period - which unfortunately I don't have the figures for, you should be OK with that though, as you've replaced it.

I don't think it's the WUR from your description.

[krnau 0]

does the fan run-on work OK? triggered by the little switch on the front left of the cam cover, this is intended to keep engine bay temps down to prevent fuel vapourising in the fuel lines causing exactly the problem you describe.

I believe the pressure accumulator should do a similar thing, by keeping the system pressure up, you also need to check the pressure the system is maintaining after engine-off for the specified period - which unfortunately I don't have the figures for, you should be OK with that though, as you've replaced it.

I don't think it's the WUR from your description.

 

 

hello, thank you for your repply :)

 

I don't have the run-on fan switch :pale: I read a thread in here some time ago, and many more KR owners didn't have it o_O

 

I have a bold in where this switch should be located :? :? :?

 

 

 

Anyway, when stopping the engine, I always turn the key up to the first position until the fan switches off.. then release the key and leave the car... so I don't think this would be causing my problem, don't you think? Please reply, thanks :):)

[davidwort 0]

try lifting the bonnet when you stop, keeping the engine bay cool, and see if that makes a difference to the starting, the fan run on switch should have a black wire that comes from the engine loom on the left hand inner wing area, that's if the car ever had one when it was built?

 

old tired injectors can cause funny starting issues too, they don't have to leak, just have poor fuel delivery and spray pattern at idle speed, worth pulling them, and spraying them into jars to check the spray pattern and flow rate see here

[krnau 0]

helllo. the thing is, once correctly idleing, the car runs perfectly without any lack of power...

 

 

May I try to start it from stone cold for just 10 secs or so, then stop it and leave one hour or so... then start it up and see what happens? what do you think about it? and what conclusions should I get from this?

 

 

thank you for your help :

[davidwort 0]

far more fuel circulates in the system back to the tank than the engine actually needs, this helps keep the fuel at a low temperature while the engine is running, problems occur when you stop the engine as heat build up in the fuel lines can cause the fuel vapourisation, that's why it would run fine once it's going, but struggle initially.

I get similar, although much less serious, lumpy running sometimes on warm starts, but that's mainly due to slightly tired old injectors.

[krnau 0]

first post updated :)

[Josh Waddi 0]

i have very similar problems with mine. it will fire up 1st time in a morning but then once exceleration is applied the engine wants to cut out. once its been running for 30 seconds or so it corrects its self.

Similar if the car has been left for a few hours, its damn near impossible to start and when it does it idles at 400ish or cuts out. it think its a misfire or cylender down on initial start.

[krnau 0]

i have very similar problems with mine. it will fire up 1st time in a morning but then once exceleration is applied the engine wants to cut out. once its been running for 30 seconds or so it corrects its self.

Similar if the car has been left for a few hours, its damn near impossible to start and when it does it idles at 400ish or cuts out. it think its a misfire or cylender down on initial start.

 

well, mine doesn't cut off. if I accelerate, it revs up but sounds like running on 3 cilynders as well :(

[Josh Waddi 0]

To be honest mate when i got it back in September 08 it was basically how you expain yours is, now 7 months down the line and its doing what i explained. Ive had a few people listen to it (not mechanics but knowledgeable) when ive started it and tried to drive away and each person has advised "its a cilynder down". :(

[krnau 0]

To be honest mate when i got it back in September 08 it was basically how you expain yours is, now 7 months down the line and its doing what i explained. Ive had a few people listen to it (not mechanics but knowledgeable) when ive started it and tried to drive away and each person has advised "its a cilynder down". :(

 

 

I have had this issue for 2 years now, and after 6 secs it begins to work correctly. don't you think that if it was a dead cilynder, it would always start badly?

 

have you had your co/timing/vaccum pipes checked for air leaks/etc ?

[Josh Waddi 0]

Ive not had anything checked as i dont know where to get it done or how much, ive just lived with it. The plan is to do a conversion so ive never really spent time on the engine just changed a few bits and bobs.

 

Its true what your saying about the cilynder being broke every start would be the same. Ive still got my mind set on it being a misfire of some sort. but i know nothing compared to the mods on here.

[aide 0]

'this takes me to think that fuel accumulator is OK?' - the accumulator maintains pressure when the pump isn't running, if ur starting from cold after long periods then this will be fine.

 

unfortuantely there's so many variables in kjet system it's difficult to diagnose from afar, my view;

 

possible 1. as you noted 'it might be a WUR malfunction when it is hot' - hot block means hot wur = higher control pressure = leaner mixture so a possibility especally when combined with an iffy under fueling injector as already suggested, but the WUR rarely goes wrong.

 

possible 2. your thermotime switch is buggered, this means when hot the cold start valve will still operate = over fueling, combined with an over fueling injector means one cylinder will be running too rich to combust. the thermotime only runs for 8-15secs (temp/ time is written on side of it) so this seems a bit too coinciental. To test simply disconect the blue connector when starting from warm.

 

do the injector test as suggested, new ones are cheapish - £20 iirc

 

really would recommend a book called 'how to tune & modify bosch fuel injection' it's got a description of a fuel pressure guage, but it's only a 100psi guage on a T shaped junction

 

bottom end of T = guage

left of T = length of fuel pipe

right of T = male fuel pipe connector

[krnau 0]

'this takes me to think that fuel accumulator is OK?' - the accumulator maintains pressure when the pump isn't running, if ur starting from cold after long periods then this will be fine.

 

unfortuantely there's so many variables in kjet system it's difficult to diagnose from afar, my view;

 

possible 1. as you noted 'it might be a WUR malfunction when it is hot' - hot block means hot wur = higher control pressure = leaner mixture so a possibility especally when combined with an iffy under fueling injector as already suggested, but the WUR rarely goes wrong.

 

possible 2. your thermotime switch is buggered, this means when hot the cold start valve will still operate = over fueling, combined with an over fueling injector means one cylinder will be running too rich to combust. the thermotime only runs for 8-15secs (temp/ time is written on side of it) so this seems a bit too coinciental. To test simply disconect the blue connector when starting from warm.

 

do the injector test as suggested, new ones are cheapish - £20 iirc

 

really would recommend a book called 'how to tune & modify bosch fuel injection' it's got a description of a fuel pressure guage, but it's only a 100psi guage on a T shaped junction

 

bottom end of T = guage

left of T = length of fuel pipe

right of T = male fuel pipe connector

 

 

 

thanks fro your help. My CSV is actually disconnected (I mean, the electrical connector).

 

I have the VW garage book of k-jetronic, but I got both of my hands burnt with butane gas so I will be some time away from DIY :(

[aide 0]

sounds nasty :shock:

 

just remembered i was supposed to send you a mail too, i'll get on it now

[krnau 0]

sounds nasty :shock:

 

just remembered i was supposed to send you a mail too, i'll get on it now

 

 

:lol: :lol: I have received it : )thanks!